Lithium fine structure

Lithium intercalation in VeOis has been studied by Stallworth et al. ° Variable-temperature Li NMR indicated considerable mobility for Li+ in the intercalated materials. The Li NMR data were compared with ESR spectra and near-edge X-ray absorption fine structure (NEXAFS) data on the same materials, and a correlation between vanadium oxidation state (from NEXAFS data) and NMR shift was observed. The authors explained the shifts in terms of different coupling mechanisms between the and shifts. The shifts were, however, extracted from static NMR experiments, and it is possible that some of the different local environments, typically revealed in a MAS spectrum, were not seen in this study. 

The splitting of these lines and of other lines that show fine structure can be accounted for by means of the energy-level diagram for lithium shown in Figure 2-9. In this diagram each of the levels 2p, 3p, 3d, and so forth isqshown as two levels, only slightly separated from one another, whereas the levels 2s, 3s, 4s, and so forth are not split. 

Lithium-12-hydroxy stearate in a synthetic ester, very fine structure ... 

A typical application of the relativistic SD equations is given in Table 6, where we compare MBPT and SD calculations of energies (relative to the ionization threshold) of 2si/2, 2pi/2, and 2ps/2 levels of lithium and singly ionized beryllium. The all-order calculations include partial waves through /max = 7. The second-order MBPT calculation is carried out in a large (n = 100) basis set and includes partial waves up to Imax = 12 The third-order values and i/extra sre calculated with n = 40 spline basis set and /max = 7. Breit and reduced mass (RM) and mass polarization (MP) corrections values are taken from [54]. The SD value of the 2p3/2 — 2pi/2 fine structure interval for Li is 0.00000156 a.u. compared with the measured value 0.000001534(2) a.u.. The corresponding theoretical and experimental values for Be" " are 0.00003001 a.u. and 0.00002998(3) a.u.. The tiny differences between the SD energies and experiment on the last line of Table 6 are probably dominated by the incomplete treatment of triple excitations. 

Rode et al. (107) carried out an electron spin resonance study of the intermediate oxides formed in the thermal decomposition of chromic anhydride. Chromium decachromate, chromium dichromate, and chromium hydroxide at room temperature, as well as the ferromagnetic compounds chromium monochromate and chromium dioxide above their Curie points at 130°, give symmetrical absorption lines 130 to 160 gauss wide with a g factor of 1.97, Shnkin and Fedorovskaia (108) studied CrgOa containing lithium, and detected fine structure in the ESR spectrum. 

Scanning. The spectrum is scanned and recorded across the complete line profile at 0.2nm per minute for perhaps 0.4 nm overall (Figure 2). The height of the lithium peak above the small CaO fine structure peak on the right is to be compared with that of the calcium standard scan. The correction is accurate to within 2% even though the Ca Li ratio is 1.6 x 10. The method is slower and requires several millilitres of sample solution. (Chemical interferences obviously are minimal in this example.)... 

Similar measurements of d-f and d-g intervals in lithium Rydberg states by Cooke et yielded fine structure intervals in accordance with the hydrogenic theory. Ruff and co-workers measured n = 15-17 f-g intervals in Cs and determined values for the effective Cs dipole and quadrupole polarizabilities. To reach the Rydberg levels the first laser excited atoms from the 6si/2 ground state to the lp-i/2 state, from which they cascaded to the 5ds/2 level. The second laser then induced the 5ds/2-16/7/2 transition. This excitation technique was first used by Lundberg and Svanberg for lifetime measurements. ... 

Using the vector model, find and give a term symbol for each fine structure state of the ls 2p excited state lithium atom. 

The most sensitive analytical line for lithium is at 670.785 nm with a characteristic concentration of Co = 0.006 mg/L in an air/acetylene flame, and a linear working range up to about Ara x = 3 mg/L. The characteristic mass at this line, using a transversely heated graphite tube atomizer, is mo = 1 pg. The lithium line at 670.785 nm is actually a doublet with a separation of about 15 pm, and it also exhibits an isotope shift of the same magnitude [150]. However line broadening in conventional atomizers is usually too pronounced, so that the individual fine structure components cannot be resolved. 

The voltage of a lithium intercalation battery varies with its state of discharge, i.e., the intercalant composition x. Subsequently more careful experiments have shown fine structure in V(x) for many intercalation system [4, 5, 7, 10] clearly observed in plots of dxIdV vs. x or V, which can be caused by a variety of physical mechanisms such as the interactions between intercalated atoms within the host or intercalation-induced stmctural phase transitions in the host. Therefore, careful measurements of dx/dV can be used a study the physics and chemistry of the intercalation process. 

Co304 with an excess of n-butyl lithium results in further lithiation of the oxide particles, but with a concomitant extrusion of very finely divided transition metal from the rock salt structure. Highly lithiated iron oxide particles are pyrophoric if exposed to air [100]. 

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